The EAP110-Outdoor does not support repeater mode. The CPE210 does, but the CPE is meant for directional links and therefore has directional antennas with a beam width of 65°, not omnidirectional antennas with 360°. Beside of this, cascading 3 repeaters will reduce the total bandwidth by a factor of 2³ for all devices. You shouldn't do this.

It's much better to set up the base AP in AP mode and have the three other APs connect to it in client mode if you really need to connect them wirelessly. For omnidirectional coverage, you could add EAP110-Outdoors to the CPEs, but I would use CPE510 (5 GHz) to avoid interferences with the EAP110-Outdoors.

pengwan wrote

Your suggestion is great, will look at having a pair of CPE510 from base to each AP's location and add another EAP110 each, maybe will reduce the number of stations to 2 instead of 3 too since the coverage should be enough.

I'm just in the progress of installing such a topology in an RV park, which has similar dimensions as your area. Works like a charm!